Injection Molding Machine Pass/Fail Determination System

The present invention relates to a pass/fail determination system used for an injection molding machine that injects a molten resin material to form a molded article.

Functions of monitoring the quality of a molded article formed by an injection molding machine includes a function of determining the quality of the molded article by setting an allowable value for each monitoring data such as pressure and temperature obtained from sensors for each shot and comparing the acquired monitoring data with the allowable value. For example, when the barrel temperature deviates from the allowable value set for the reference, the molded article formed by the shot is determined as a defective article.

However, such allowable value setting requires a certain degree of experience on a worker. For this reason, some of pass/fail determination methods in the conventional injection molding machine uses a method capable of easily and reliably performing adjustment to a good state without a burden on a skilled worker. For example, a pass/fail determination method in a plasticizing step in an injection molding machine described in Patent Document 1 obtains an MD value based on a reference data value aggregated from data of a parameter related to behavior of a molding material at the time of performing a predetermined shot and a data value aggregated from data of a parameter at the time of a certain shot, and makes a pass/fail determination of an operation in the plasticizing step based on the magnitude of the obtained MD value.

Patent Document 1: JP 2008-246734 A

Here, exemplary methods of acquiring monitoring data during molding on an injection molding machine include a method of predefining a timing at which most characteristic data can be acquired in one molding cycle and acquiring data on each one point at the timing predetermined in each cycle. Regarding the quality of the molded article, by comparing the monitoring data thus acquired with an allowable value of the monitoring data, it is possible to perform pass/fail determination of the molded article, being a product obtained by molding.

Another method of determining the quality of the molded article based on the monitoring data is a method of determining the quality using waveform data acquired during injection molding performed by an injection molding machine. For example, an injection pressure waveform during filling of a resin material into a mold is recorded. When a maximum value exceeds a predetermined threshold, the article is determined as a defective article assuming a phenomenon such as overpacking; when the maximum value of the injection pressure waveform does not exceed the threshold, the article is determined as a non-defective article.

The pass/fail determination using monitoring data can use a method of performing the determination using a monitoring data group including each one point or a method of performing the determination using the waveform data in this manner. The method of performing pass/fail determination using the data of one point enables determination of a defect due to a combined factor of a plurality of pieces of data by using multivariate analysis. On the other hand, in the pass/fail determination performed from the waveform data, the pass/fail determination is performed using features such as the maximum value or the minimum value of the waveform data, independent of the determination using the monitoring data group.

In the pass/fail determination using the monitoring data, the determination using the monitoring data group including each one point and the determination using the waveform data are performed independently. Therefore, there would be no problem as long as the defect phenomenon can be grasped only with the monitoring data group or the waveform data, but the defect phenomenon includes a case having difficulty of making determination unless both the monitoring data group and the waveform data are analyzed in association with each other. However, the monitoring data group and the waveform data have different data formats, disabling computation in the same dimension, making it very difficult to determine molding defect by combining the monitoring data group and the waveform data.

The present invention has been made in view of the above, and an object of the present invention is to provide an injection molding machine pass/fail determination system capable of performing molding defect determination by combining a monitoring data group and waveform data in the same dimension.

In order to solve the above problem and achieve the object, an injection molding machine pass/fail determination system according to the present invention includes: a setting timing data acquisition module configured to acquire a plurality of pieces of setting timing data being monitoring data at preset timings among pieces of monitoring data of an injection molding machine when molding a molded article by the injection molding machine; a waveform data acquisition module configured to acquire waveform data being the monitoring data continuous in a predetermined period among the pieces of monitoring data; a sample point data acquisition module configured to acquire a plurality of pieces of sample point data being data at a plurality of sample points at different time points in the waveform data acquired by the waveform data acquisition module; a combined data generation module configured to combine a monitoring data group and the plurality of pieces of sample point data to generate combined data, the monitoring data group including the plurality of pieces of setting timing data acquired by the setting timing data acquisition module, the plurality of pieces of sample point data being acquired by the sample point data acquisition module; and a pass/fail determination module configured to determine whether a defective article has occurred in the molded article molded by the injection molding machine, based on the combined data generated by the combined data generation module.

An injection molding machine pass/fail determination system according to the present invention has an effect of being able to perform molding defect determination by combining a monitoring data group and waveform data in the same dimension.

Hereinafter, an embodiment of a pass/fail determination system of an injection molding machine according to the present disclosure will be described in detail with reference to the drawings. Note that the present invention is not limited by the embodiment. In addition, constituent elements in the following embodiments include those that can be replaced by those skilled in the art and can be easily conceived, or those that are substantially the same.

is a schematic diagram illustrating a configuration example of a pass/fail determination systemof an injection molding machineaccording to an embodiment. In the following description, the vertical direction in the normal use state of the injection molding machinewill be also described as the vertical direction in the injection molding machine, while the horizontal direction in the normal use state of the injection molding machinewill be also described as the horizontal direction in the injection molding machine.

The injection molding machineaccording to the present embodiment includes an injection deviceand a mold clamping device. The injection deviceand the mold clamping deviceare disposed on a framelocated at a lower end of the injection molding machine. The injection molding machinemelts a molding material into a plasticizing material by the injection device, and cools and solidifies the plasticizing material injected from the injection deviceby the mold clamping device, making it possible to manufacture various types of desired molded articles.

The injection deviceincludes a heating barrel, a screw, a weighing unit, and an injection device drive unit. The heating barrelis capable of internally heating and melting the molding material into a plasticizing material. In addition, the heating barrelincludes, on its one end side, a nozzleto inject a plasticizing material, and is connected, on the other end side, to a hopperfor raw material charging. The screwis disposed in the heating barreland is movable in the axial direction inside the heating barrel.

The weighing unitrotates the screwin the heating barrelto enable introduction of a resin as a molding material into the heating barrelfrom the hopper.

The injection device drive unitcan move the screwin the horizontal direction inside the heating barrel. In addition, the injection device drive unitoperates, inside the heating barrel, so as to move the screwtoward the nozzlein a state where the molten molding material is stored in the end portion side where the nozzleis located, making it possible to extrude the molding material from the nozzle. This enables the molding material in the heating barrelto be injected from the nozzle.

The mold clamping deviceincludes a stationary platen, a movable platen, a mold clamping drive mechanism, and an extrusion mechanism. The stationary platenis disposed on the frameso as to be fixed to the frame. The movable platenis disposed on the frameon the side opposite to the position of the injection devicewith respect to the stationary platenso as to be movable with respect to the stationary platen. There is provided a stationary moldattached to a surface of the stationary platenon a side where the movable platenis located, and a movable moldis attached to a surface of the movable platenon a side where the stationary platenis located. The movable moldattached to the movable platenfaces the stationary moldattached to the stationary platen. When the movable platenapproaches the stationary platen, the movable moldapproaches the stationary moldso as to be assembled with the stationary mold.

The mold clamping drive mechanismcan move the movable platenrelative to the stationary platen. By moving the movable platenrelative to the stationary platen, it is possible to perform mold closing of the movable moldand the stationary moldor mold opening of the movable moldand the stationary mold. In the present embodiment, the mold clamping drive mechanismincludes a mechanism referred to as a toggle mechanism, and the movable platencan be moved relative to the stationary platenby the toggle mechanism.

The extrusion mechanismincludes an extrusion member, which extrudes the molded article after molding attached to the inner surface of the movable mold, making it possible to remove the molded article after molding from the movable mold.

The injection molding machineincludes: a control devicethat performs various types of control of the injection molding machine; an input unitthrough which an operator performs input operation to the injection molding machine; and a display unitthat displays various types of information. The input unitand the display unitare both connected to the control device. The input unittransmits information obtained by input operation to the control device. In addition, the display unitdisplays information transmitted from the control device. The input unitand the display unitmay be configured separately, or may be integrally formed by being configured by a display referred to as a touch panel display.

The control deviceis connected to devices like various actuators such as a motor to be a power source of the operation in the injection molding machineand various sensors that acquire information during the operation of the injection molding machine. With this configuration, the control devicecan control the injection molding machineby transmitting a control signal to the actuator of the injection molding machinewhile acquiring information during operation of the injection molding machineby the sensor.

is a diagram illustrating the control deviceillustrated in. The control deviceincludes a processing unit, a storage unit, and an input/output unit. The processing unitincludes a central processing unit (CPU) that performs arithmetic processing, and devices functioning as memory that stores various types of information, such as random access memory (RAM) and read only memory (ROM). All or a part of each function of the processing unitis implemented by loading an application program stored in the ROM into the RAM and executing the program by the CPU to perform data reading and writing on the RAM or the ROM.

The storage unitis a storage device that is electrically connected to the processing unitand stores information. When the control devicecontrols the injection molding machine, the information acquired from the injection molding machineby the processing unitand the information calculated by the processing unitare stored in the storage unit, or the information stored in the storage unitis retrieved by the processing unitand used for controlling the injection molding machine.

Individual functions implemented by the processing unitmay be pre-stored in the storage unitas a program. In this case, the processing unitexecutes individual functions by retrieving a program stored in the storage unitby the processing unitand executing an operation according to the program by the processing unit. Furthermore, the storage unitmay be provided integrally with the control device, or may be detachable from the control device.

The input/output unitis a unit functioning as an interface, configured to input and output signals to and from a device outside the control device. That is, the input/output unitis connected with various actuators and various sensors of the injection molding machineconnected to the control device, the input unit, and the display unit. The processing unitincluded in the control devicetransmits and receives signals to and from these external devices via the input/output unit.

The processing unitincludes, as functional units, a monitoring data acquisition module, a reference value acquisition module, an allowable value acquisition module, a monitoring data determination module, a basic data generation module, a monitoring data extraction module, a high-influence monitoring data extraction module, a determination parameter calculation module, a molding parameter calculation module, a recommended value calculation module, a pass/fail determination module, and an abnormality data extraction module.

Among these units, the monitoring data acquisition modulecan acquire monitoring data, which is detection results obtained by various sensors included in the injection molding machinewhen the injection molding machineis in operation. Examples of the monitoring data include the temperature at which the molding material is melted by the heating barrelof the injection deviceof the injection molding machine, the time used for introducing the molding material into the heating barreland weighing the molding material, and the rotation speed of the screw. The monitoring data acquisition modulestores the acquired monitoring data in the storage unittogether with the time of acquisition. That is, the monitoring data acquisition modulestores the acquired monitoring data in the storage unitin association with the date and time of acquisition.

In addition, the monitoring data acquisition moduleincludes: a setting timing data acquisition module; a waveform data acquisition module; a sample point data acquisition module; and a combined data generation module. The setting timing data acquisition moduleand the waveform data acquisition moduleacquire monitoring data of mutually different forms, and the sample point data acquisition moduleand the combined data generation moduleare able to handle the monitoring data of different forms acquired by the setting timing data acquisition moduleand the waveform data acquisition moduleas similar data.

is a diagram illustrating an example of setting timing data. The setting timing data acquisition moduleincluded in the monitoring data acquisition modulecan acquire a plurality of pieces of setting timing data, which are monitoring data obtained at preset timings among the monitoring data of the injection molding machinewhen molding the molded article by the injection molding machine. The setting timing dataacquired by the setting timing data acquisition moduleis monitoring data obtained at a timing set for each monitoring data as a timing at which the most characteristic monitoring data is observed in one molding cycle of forming the molded article by the injection molding machine.

The setting timing data acquisition moduleacquires a plurality of pieces of monitoring data to be acquired as the setting timing data, as the setting timing datafor each molding cycle during the forming of the molded article in the injection molding machine. With this operation, for example, as illustrated in, the setting timing data acquisition moduleacquires a monitoring data groupincluding a plurality of pieces of setting timing datafor each molding cycle in the injection molding machine, and stores each setting timing datain the storage unitin association with the acquisition date and time.

is a diagram illustrating an example of waveform data. The waveform data acquisition moduleincluded in the monitoring data acquisition moduleis capable of acquiring the waveform data, which is continuous monitoring data for a predetermined period, among the monitoring data of the injection molding machineobtained in the forming of the molded article by the injection molding machine. The waveform dataacquired by the waveform data acquisition moduleis monitoring data, which is acquired as continuous data including monitoring data with its values changing with the lapse of time, in one molding cycle of the forming of the molded article by the injection molding machine, and which is acquired in association with the time in the molding cycle. That is, unlike the setting timing data acquisition module, the waveform data acquisition moduleacquires not monitoring data at a specific timing in one molding cycle but entire monitoring data whose value changes in one molding cycle including a state of the change.

is one example of the waveform dataregarding a filling pressure when the injection devicefills the mold with a resin during molding by the injection molding machine. Regarding the filling pressure at the time of molding by the injection molding machine, the pressure changes in one molding cycle as illustrated in, and the waveform data acquisition moduleacquires the entire value of the pressure that changes with the lapse of time as the waveform dataincluding the state of the change.

The waveform data acquisition moduleacquires a plurality of pieces of monitoring data to be acquired as the waveform datafor each molding cycle during the forming of the molded article on the injection molding machine, as the waveform data. With this operation, the waveform data acquisition moduleacquires a plurality of pieces of waveform datafor each molding cycle in the injection molding machine, and stores each piece of waveform datain the storage unitin association with the acquisition date and time.

The monitoring data acquired as the waveform dataincludes not only the filling pressure, but also data such as the temperature of the mold, the flow rate of cooling water for cooling the mold, the mold internal pressure which is the pressure in the mold when the resin is filled in the mold. All pieces of monitoring data are acquired as the waveform databy the waveform data acquisition modulefor each molding cycle, and are stored in the storage unitin association with the acquisition date and time.

is a diagram illustrating an example of sample point data. The sample point data acquisition moduleincluded in the monitoring data acquisition moduleacquires a plurality of pieces of sample point data, which are pieces of data at a plurality of sample pointsbeing temporally different time points, in the waveform dataacquired by the waveform data acquisition module. Here, the sample pointis a point set in plurality at different time points on the waveform dataacquired by the waveform data acquisition module, being a point to be used for extracting values of the waveform data.

For example, the number of samples to be extracted from one piece of waveform datais preset, and the sample pointis set at a time interval at which the number of samples can be obtained satisfactorily for one piece of waveform data. Alternatively, the sample pointsmay be directly set at optionally defined time intervals for one piece of waveform data.

The sample point data acquisition moduleacquires monitoring data at the position of the sample pointset for the waveform data, as the sample point data. Since the sample pointis set in plurality for one piece of waveform data, the sample point data acquisition moduleacquires a plurality of pieces of sample point datafrom one piece of waveform datacorresponding to the sample points, for example, as illustrated in.

is a diagram illustrating an example of combined data.is a diagram illustrating a state in which the combined dataof a plurality of shots is acquired. The combined data generation moduleincluded in the monitoring data acquisition modulecombines the monitoring data groupincluding the plurality of pieces of setting timing dataacquired by the setting timing data acquisition moduleand the plurality of pieces of sample point dataacquired by the sample point data acquisition moduleto generate the combined data. With this operation, the combined data generation modulecan handle the plurality of pieces of setting timing dataacquired by the setting timing data acquisition moduleand the plurality of pieces of sample point dataacquired by the sample point data acquisition modulefrom the waveform dataacquired by the waveform data acquisition module, as monitoring data of the similar type which are independent from each other.

Since the setting timing dataand the sample point dataare acquired for each molding cycle in the injection molding machine, the combined data generation modulegenerates the combined datafor each molding cycle, that is, generates the combined datafor each shot at the injection molding performed by the injection molding machine.

In, the sample point datato be combined with the monitoring data groupis illustrated as the sample point dataof the waveform dataregarding the filling pressure. However, the sample point datato be combined with the monitoring data groupmay be the sample point dataof the waveform dataother than the filling pressure. The sample point datato be combined with the monitoring data groupmay be the sample point dataof a plurality of pieces of waveform data.

The reference value acquisition moduleacquires a reference value of monitoring data, related to the time of operation of the injection molding machineand having been input by the user of the injection molding machineusing the input unit. The monitoring data here includes both the setting timing dataacquired by the setting timing data acquisition moduleand the sample point dataacquired by the sample point data acquisition module. The similar applies to the following description. The reference value acquisition modulestores the acquired reference value of the monitoring data in the storage unit.

The allowable value acquisition moduleacquires an allowable value for the reference value of the monitoring data, which is related to the time of operation of the injection molding machineand having been input by the user of the injection molding machineusing the input unit. The allowable value acquisition modulestores the acquired allowable value for the reference value of the monitoring data in the storage unit.

The monitoring data determination modulecompares the monitoring data acquired by the monitoring data acquisition modulewith the reference value acquired by the reference value acquisition moduleand the allowable value acquired by the allowable value acquisition module, and determines whether the monitoring data is within the range of the allowable value.

The basic data generation modulegenerates basic data in which a determination result as to whether the molded article formed by the injection molding machineis a non-defective article or a defective article is associated with monitoring data of the injection molding machinewhen the molded article is formed, that is, the monitoring data acquired by the monitoring data acquisition module. That is, the basic data generation modulegenerates basic data in which a determination result as to whether the molded article formed by the injection molding machineis a non-defective article or a defective article is associated with the combined datagenerated by the combined data generation moduleincluded in the monitoring data acquisition module. The basic data generated by the basic data generation moduleis stored in the storage unitin association with the date and time of acquisition of the monitoring data or the date and time of forming the molded article.

From the basic data generated by the basic data generation module, the monitoring data extraction moduleextracts a plurality of pieces of non-defective article monitoring data which are monitoring data at the time of forming a non-defective article, and a plurality of pieces of defective article monitoring data which are monitoring data at the time of forming a defective article. That is, since the basic data is data in which the determination result of the molded article formed by the injection molding machineis associated with the monitoring data at the time of forming the molded article, namely the combined data. Therefore, the non-defective article monitoring data and the defective article monitoring data are distinguished and extracted by the determination results the molded article and the monitoring data at the time of forming of each molded article. That is, the monitoring data extraction moduleextracts the setting timing dataand the sample point dataincluded in the combined dataassociated with the determination result of the molded article, as the non-defective article monitoring data or the defective article monitoring data.

In addition, the monitoring data extraction moduleextracts the non-defective article monitoring data and the defective article monitoring data of the same type for each defect type of the defective article. That is, the monitoring data extraction moduleextracts the setting timing dataor the sample point dataextracted as the defective article monitoring data, as well as the setting timing dataor the sample point dataof the same type as the setting timing dataor the sample point datain the non-defective article monitoring data, in association with the defective type of the defective article. The non-defective article monitoring data and the defective article monitoring data extracted by the monitoring data extraction moduleare stored in the storage unit.

Examples of the defect type herein include short shot, burr, flow mark, silver streak, jetting, burn, cloudiness, whitening, weld line, warpage, crack, yellowing, sink mark, and void.

The short shot is a defect in a state where the resin is not completely filled. The burr is a defect of occurrence of a surplus portion on the outer periphery of the molded article, caused by the molten material entering the gap of the mold. The flow mark is a defect appearing on the surface of the molded article as a striped pattern caused by the resin flowing in the mold. The silver streak is a defect appearing as a white streak occurring along the flow of the resin starting from a gate portion, which is an opening to a flow path of the resin onto the molded article in the mold.

The jetting is a defect appearing as a trace of the resin flowing after passing through the gate. Burn is a defect as a burnt end portion of the resin. The cloudiness is a defect appearing as a surface that becomes cloudy white particularly in molding of a transparent resin. Whitening is a defect appearing as a locally stretched portion formed by application of an excessive force on a solidified resin. The weld line is a defect occurring as a line-shaped trace appearing at a meeting portion of flow fronts branched by the cavity shape of the mold.